U.S. patent application number 17/416275 was filed with the patent office on 2022-02-17 for method for limiting current in-rush in automotive lighting devices.
This patent application is currently assigned to VALEO VISION. The applicant listed for this patent is VALEO VISION. Invention is credited to Jose AFONSO, David BOUDIKIAN, Clement FABRIS.
Application Number | 20220053620 17/416275 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-17 |
United States Patent
Application |
20220053620 |
Kind Code |
A1 |
BOUDIKIAN; David ; et
al. |
February 17, 2022 |
METHOD FOR LIMITING CURRENT IN-RUSH IN AUTOMOTIVE LIGHTING
DEVICES
Abstract
A method for limiting current in-rush in automotive lighting
devices. By controlling the state of a switching circuit that is
used to selectively connect a power supply to an automotive
lighting device, the invention allows for selectively limiting the
intensity of the current that is supplied to the lighting device.
In accordance with preferred embodiments, this advantage is
achieved by relying on electronic components that are nowadays used
for different purposes.
Inventors: |
BOUDIKIAN; David; (Bobigny
Cedex, FR) ; FABRIS; Clement; (Bobigny Cedex, FR)
; AFONSO; Jose; (Bobigny Cedex, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VALEO VISION |
Bobigny Cedex |
|
FR |
|
|
Assignee: |
VALEO VISION
Bobigny Cedex
FR
|
Appl. No.: |
17/416275 |
Filed: |
December 5, 2019 |
PCT Filed: |
December 5, 2019 |
PCT NO: |
PCT/EP2019/083852 |
371 Date: |
June 18, 2021 |
International
Class: |
H05B 45/3725 20060101
H05B045/3725; H05B 45/50 20060101 H05B045/50; H05B 45/325 20060101
H05B045/325; H02M 3/156 20060101 H02M003/156; H02H 9/00 20060101
H02H009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2018 |
EP |
18215631.5 |
Claims
1. A control method for a driver device of an automotive lighting
device, wherein the driver device is suitable for supplying
electricity to said lighting device and comprises a first input for
receiving an electricity supply, a switching circuit for
selectively connecting said first input to the lighting device and
for selectively limiting the intensity of the electric current
provided to the lighting device, and a second input for receiving a
control signal for the switching circuit, wherein the method
comprises the steps of: detecting the presence of an electricity
supply on said first input using a detection circuit; upon said
detection, controlling said switching circuit using a control
signal, so that said first input is connected to the lighting
device, and so that the intensity of the electric current flowing
through the first input is limited to a predetermined value.
2. The method according to claim 1, wherein upon said detection,
the controlling step comprises limiting the intensity of the
electric current flowing through the first input to a predetermined
value for a predetermined timespan.
3. The method according to claim 2, wherein the controlling step
comprises the cancellation of said limitation after said
predetermined timespan has elapsed.
4. The method according to claim 1, wherein the switching circuit
comprises a field effect transistor having a linear mode, and
wherein upon said detection, the controlling step comprises driving
the transistor into linear mode using said control signal, so that
the transistor acts as a resistance that limits the intensity of
the electric current provided to the lighting device.
5. The method according to claim 1, wherein the switching circuit
comprises a capacitor.
6. The method according to claim 1, wherein the control signal
comprises a pulse width modulated, PWM, signal.
7. The method according to claim 1, wherein the electronic
components of said switching circuit at least partly implement a
reverse current protection circuit of said driver device.
8. A control method for a driver device of an automotive lighting
device, wherein the driver device is suitable for supplying
electricity to said lighting device and comprises a plurality of
first inputs for selectively receiving any of a plurality of
electricity supplies, wherein each first input is associated with a
switching circuit for selectively connecting said first input to
the lighting device and for selectively limiting the intensity of
the electric current provided to the lighting device, the driver
device further comprising a plurality of second inputs for
receiving a control signal for each switching circuit, wherein the
method comprises the steps of: detecting the presence of an
electricity supply on one of said first inputs using a detection
circuit; upon said detection, controlling the corresponding
switching circuit using a control signal, so that said first input
is connected to the lighting device, and so that the intensity of
the electric current flowing through the first input is limited to
a predetermined value.
9. A control system comprising a control unit and a driver device
of an automotive lighting device, wherein the driver device is
suitable for supplying electricity to said lighting device and
comprises a first input for receiving an electricity supply, a
switching circuit for selectively connecting said first input to
the lighting device and for selectively limiting the intensity of
the electric current provided to the lighting device, and a second
input for receiving a control signal for the switching circuit, the
control unit comprising: a detection circuit for detecting the
presence of an electricity supply on said first input; a control
signal generator which is configured for generating a control
signal for controlling said switching circuit upon said detection,
so that said first input is connected to the lighting device, and
so that the intensity of the electric current flowing through the
first input is limited to a predetermined value.
10. The control system according to claim 9, wherein the control
unit comprises a microcontroller device operatively connected to
said driver device.
11. The control system according to claim 9, wherein the driver
device comprises at least one DC/DC converter.
12. The method according to claim 2, wherein the switching circuit
comprises a field effect transistor having a linear mode, and
wherein upon said detection, the controlling step comprises driving
the transistor into linear mode using said control signal, so that
the transistor acts as a resistance that limits the intensity of
the electric current provided to the lighting device.
13. The method according to claim 2, wherein the switching circuit
comprises a capacitor.
14. The method according to claim 2, wherein the control signal
comprises a pulse width modulated, PWM, signal.
15. The method according to claim 2, wherein the electronic
components of said switching circuit at least partly implement a
reverse current protection circuit of said driver device.
16. The control system according to claim 10, wherein the driver
device comprises at least one DC/DC converter.
17. The method according to claim 3, wherein the switching circuit
comprises a field effect transistor having a linear mode, and
wherein upon said detection, the controlling step comprises driving
the transistor into linear mode using said control signal, so that
the transistor acts as a resistance that limits the intensity of
the electric current provided to the lighting device.
18. The method according to claim 3, wherein the switching circuit
comprises a capacitor.
19. The method according to claim 3, wherein the control signal
comprises a pulse width modulated, PWM, signal.
20. The method according to claim 3, wherein the electronic
components of said switching circuit at least partly implement a
reverse current protection circuit of said driver device.
Description
[0001] The invention lies in the field of driver devices for
automotive lighting devices, and in particular for automotive
lighting devices involving electroluminescent components, such as
light emitting diodes, LEDs.
[0002] It is increasingly common to use electroluminescent
semiconductor components, such as light emitting diodes, LEDs in
automotive lighting applications. LEDs are small components capable
of producing beams having high luminosity at relatively low supply
current intensities. Using LEDs, interesting lighting contours may
be designed, while at the same time both space and electrical power
is saved, as compared to incandescent light sources. When a voltage
difference of a value equal or larger than a LED's forward voltage
is applied to its two terminals, an electrical current flow through
the LED and photons are emitted. Generally, the luminescence of a
LED is an increasing function of the electrical current intensity
that passes through it. As the luminescence is required to conform
to predetermined regulations, it is important to carefully drive
the intensity of the electrical current supplied to LEDs. It is
known to use driver devices for driving the power supply of a LED,
which generally use a DC/DC converter circuit to transform an
electrical current having a first intensity, as supplied for
example by an internal source of an automotive vehicle, such as a
battery, into an electrical current having a second intensity,
which is appropriate to power the LEDs.
[0003] When a lighting function using such a driver device is
switched on, a current in-rush having an intensity that is larger
than the average input current intensity is generally observed.
This is due, for example but not only, to the capacitors in the
converter circuit, which need to charge and which therefore draw a
large electrical current initially. The in-rush current may
translate may be falsely detected as an overload on the LED driver
by the automotive vehicles body controller module. The latter may
thus rais a false alert and disable the driver.
[0004] This problem also arises in architectures that use a single
switched mode converter circuit having multiple power supply inputs
that may be selectively used, for example to supply different
current intensities to different lighting functions of an
automotive vehicle, such as parking lights, PL, turn indicator, TI
or other. The resources of the converter circuit are shared over
time by different lighting functions. When the input power supply
of the converter circuit is switched from a first to a second
input, an in-rush current may be observed. The issue arises
therefore not only upon initialisation of the lighting function,
but routinely at any time when power inputs are switched, which is
a common process.
[0005] It is an objective of the present invention to provide a
method and system which overcomes at least some of the
disadvantages of the prior art.
[0006] In accordance with a first aspect of the invention, a
control method for a driver device of an automotive lighting device
is proposed. The driver device is suitable for supplying
electricity to said lighting device and comprises a first input for
receiving an electricity supply, a switching circuit for
selectively connecting said first input to the lighting device and
for selectively limiting the intensity of the electric current
provided to the lighting device, and a second input for receiving a
control signal for the switching circuit. The control method is
remarkable in that it comprises the steps of: [0007] detecting the
presence of an electricity supply on said first input using a
detection circuit; [0008] upon said detection, controlling said
switching circuit using a control signal, so that said first input
is connected to the lighting device, and so that the intensity of
the electric current flowing through the first input is limited to
a predetermined value.
[0009] Preferably, upon said detection, the controlling step may
comprise limiting the intensity of the electric current flowing
through the first input to a predetermined value for a
predetermined timespan.
[0010] The controlling step may preferably comprise the
cancellation of said limitation after said predetermined timespan
has elapsed. After said predetermined timespan, the switching
circuit may preferably be controlled to connect said first input to
said lighting device.
[0011] Preferably, the switching circuit may comprise a field
effect transistor having a linear mode. Upon said detection, the
controlling step may further preferably comprise driving the
transistor into linear mode using said control signal, so that the
transistor acts as a resistance that limits the intensity of the
electric current provided to the lighting device.
[0012] Preferably, the switching circuit may comprise a
capacitor.
[0013] The control signal may preferably comprise a pulse width
modulated, PWM, signal.
[0014] Preferably, the electronic components of said switching
circuit may at least partly implement a reverse current protection
circuit of said driver device.
[0015] According to another aspect of the invention, a control
method for a driver device of an automotive lighting device is
proposed. The driver device is suitable for supplying electricity
to said lighting device and comprises at least one first input for
selectively receiving an of electricity supply, wherein each first
input is associated with a switching circuit for selectively
connecting said first input to the lighting device and for
selectively limiting the intensity of the electric current flowing
through the first input, the driver device further comprising at
least one second input for receiving a control signal said
switching circuit or switching circuits. The control method is
remarkable in that it comprises the steps of: [0016] detecting the
presence of an electricity supply on one of said first inputs using
a detection circuit; [0017] upon said detection, controlling the
corresponding switching circuit using a control signal, so that
said first input is connected to the lighting device, and so that
the intensity of the electric current flowing through the first
input is limited to a predetermined value.
[0018] According to another aspect of the invention, a control
method for a driver device of an automotive lighting device is
proposed. The driver device is suitable for supplying electricity
to said lighting device and comprises a plurality of first inputs
for selectively receiving any of a plurality of electricity
supplies, wherein each first input is associated with a switching
circuit for selectively connecting said first input to the lighting
device and for selectively limiting the intensity of the electric
current flowing through the first input, the driver device further
comprising a plurality of second inputs for receiving a control
signal for each switching circuit. The control method is remarkable
in that it comprises the steps of: [0019] detecting the presence of
an electricity supply on one of said first inputs using a detection
circuit; [0020] upon said detection, controlling the corresponding
switching circuit using a control signal, so that said first input
is connected to the lighting device, and so that the intensity of
the electric current flowing through the first input is limited to
a predetermined value.
[0021] According to yet another aspect of the invention a computer
program is provided, which, when run on a computer, leads the
computer to realize the method steps in accordance with aspects of
the invention.
[0022] A computer program product is further provided. It comprises
a computer readable medium on which the computer program in
accordance with an aspect of the invention is stored.
[0023] According to a further aspect of the invention, a control
system comprising a control unit and a driver device of an
automotive lighting device is provided. The driver device is
suitable for supplying electricity to said lighting device and
comprises a first input for receiving an electricity supply, a
switching circuit for selectively connecting said first input to
the lighting device and for selectively limiting the intensity of
the electric current provided to the lighting device, and a second
input for receiving a control signal for the switching circuit. The
control system is remarkable in that the control unit comprises:
[0024] a detection circuit for detecting the presence of an
electricity supply on said first input; [0025] a control signal
generator which is configured for generating a control signal for
controlling said switching circuit upon said detection, so that
said first input is connected to the lighting device, and so that
the intensity of the electric current provided to the lighting
device is limited to a predetermined value.
[0026] The control unit may preferably comprise a microcontroller
device operatively connected to said driver device.
[0027] Preferably, the driver device may comprise at least one
DC/DC converter. The converter may preferably comprise a switched
mode converter circuit. The converter may preferably comprise a
buck architecture, a boost architecture or a combined buck/boost
architecture. Preferably, the converter may be a Single Ended
Primary Inductor Convertor, SEPIC.
[0028] By using the driver control method in accordance with
aspects of the invention, it becomes possible to limit the
intensity of the in-rush current that arises when for example a LED
driver is switched on, or when one among a plurality of available
power inputs is connected to the driver. The in-rush current is
smoothed by driving a switch that connects the driver to the power
input first into a linear mode, wherein it acts basically like a
resistance, before fully closing it. While in linear mode, the
switch opposes itself to the flow of the in-rush current. As the
in-rush current intensity is limited, a false overload detection is
avoided. By applying the method as described herein, it becomes
thus for example possible to conform to existing automotive
lighting regulations in scenarios where this was not possible using
known methods. Field effect transistors are often used as power
switched in reverse current protection circuits for LED drivers.
The method in accordance with aspects of the invention may be
advantageously implemented by using these existing hardware
components instead of requiring the addition of further hardware
components. Indeed, a MOSFET power switch may be driven into linear
mode for a small time, by applying the appropriate control signal
to its gate terminal.
[0029] Several embodiments of the present invention are illustrated
by way of figures, which do not limit the scope of the invention,
wherein:
[0030] FIG. 1 provides a schematic illustration of system according
to a preferred embodiment of the invention, for implementing the
method according to a preferred embodiment of the invention;
[0031] FIG. 2 provides a schematic illustration of system according
to a preferred embodiment of the invention, for implementing the
method according to a preferred embodiment of the invention;
[0032] FIG. 3 provides a schematic illustration of system according
to a preferred embodiment of the invention, for implementing the
method according to a preferred embodiment of the invention;
[0033] This section describes features of the invention in further
detail based on preferred embodiments and on the figures, without
limiting the invention to the described embodiments. Unless
otherwise stated, features of one described embodiment may be
combined with additional features of another described embodiment.
Similar features of the invention are referenced with similar
reference numbers, wherein a reference number for a given feature
is incremented by one hundred when switching from one embodiment of
the invention to the next. For example, reference numbers 110, 210
and 310 each refer to a driver device as used in three different
embodiments of the invention.
[0034] The description focuses on those aspects that are relevant
for understanding the method and system in accordance with the
invention. Driver devices and automotive lighting devices comprise
other components that are well known in the art, which will not be
explicitly mentioned. These include for example a heat dissipator,
optical lenses, or structures for holding the respective components
in place.
[0035] FIG. 1 illustrates a preferred embodiment of a control
system 100 that includes a driver device 110 of an automotive
lighting device 10. The lighting device is schematically
illustrated as comprising a series string of light emitting diodes,
LED, but the invention is not limited to this example. The driver
device is suitable for supplying electricity to the lighting device
and comprises electronic circuitry to that effect. In particular,
the driver device comprises means for receiving a first input 112.
The first input 112 is an electricity supply, as provided for
example by an electricity source that is internal to the automotive
vehicle, such as a battery. The driver device further comprises a
switching circuit 114 for selectively connecting said first input
to the lighting device and for selectively limiting the intensity
of the electric current flowing through the first input. In order
to control the state of the switching circuit 114, a second input
116 for receiving a control signal for the switching circuit is
provided. The driver device may further comprise other
non-illustrated circuitry, for example a known converter circuit.
The control method of the switching circuit is implemented by a
controlling unit 120, which may for example be implemented using a
microcontroller device programmed to that effect. The controlling
unit 120 generates on one of its outputs, functionally connected to
the switching circuit 114, a control signal that carries the
controls addressed to the switching circuit. The control method
comprises the steps of: [0036] detecting the presence of an
electricity supply on said first input using a detection circuit
that is part of the controlling unit 120; [0037] upon said
detection, controlling the switching circuit 114, so that the power
supply input 112 is connected to the lighting device, and so that
the intensity of the electric current flowing through the first
input is limited to a predetermined value.
[0038] The predetermined value is a current threshold which may be
implemented by various electrical components of the switching
circuit. Typically, the limitation is active for about 1 to 2
milliseconds, after which the in-rush phenomenon is generally no
longer noticeable. The limitation may as well be active for a
shorter or longer period. Past this predetermined time, the control
signal 116 closes the switching circuit completely without limiting
the supplied current intensity.
[0039] FIG. 2 illustrates another embodiment of power supply system
200 for implementing a preferred embodiment of the method in
accordance with aspects of the invention. The system 200 includes a
driver device 210 of an automotive lighting device 10. The driver
device is suitable for supplying electricity to the lighting device
and comprises electronic circuitry to that effect. In particular,
the driver device comprises means for receiving a first input 212.
The first input 212 is an electricity supply, as provided for
example by an electricity source that is internal to the automotive
vehicle, such as a battery. The driver device further comprises a
switching circuit 214 for selectively connecting said first input
to the lighting device and for selectively limiting the intensity
of the electric current provided to the lighting device. In order
to control the state of the switching circuit 214, a second input
216 for receiving a control signal for the switching circuit is
provided. The driver device may further comprise other circuitry,
for example a known converter circuit 215. Once the power supply
212 is connected through the switching circuit 214 to the lighting
device 10, the converter circuit 215 converts the input current
into a charge current of appropriate intensity for powering the
lighting device. The converter circuit may for example comprise a
buck converter for lowering the power, a boost converter for
raising the power, or a combined boost/buck architecture. It is for
example known in the art to use switched mode converter circuits
such as a single ended primary inductor converter, SEPIC. In such
converters, the performance of the converter is controlled using a
switching signal that is not illustrated in the context of the
present invention. The switching signal is applied to a control
switch of the converter circuit, thereby defining its duty cycle.
The control method of the switching circuit 214 is implemented by a
controlling unit 220, which may for example be implemented using a
microcontroller device programmed to that effect. The controlling
unit 220 generates on one of its outputs, functionally connected to
the switching circuit 214 through resistance R1, a control signal
216 that carries the controls addressed to the switching circuit.
The control method comprises the steps of: [0040] detecting the
presence of an electricity supply on said first input using a
detection circuit that is part of the controlling unit 220; [0041]
upon said detection, controlling the switching circuit 214, so that
the power supply input 212 is connected to the lighting device, and
so that the intensity of the electric current flowing through the
first input is limited to a predetermined value.
[0042] The switching circuit 214 shown in FIG. 2 is also used to
implement a reverse current protection for the converter circuit
215. The state of the MOSFET transistors Q1 and Q2 is driven by
control signal 216 through the circuit implemented by the Zener
diode D1, the capacitor C1 and the resistance R2. Advantageously,
the control signal 216 is a pulse width modulated PWM signal, which
is a binary periodic signal having an ON state and an OFF state,
and which is characterized by its duty cycle, i.e. the ratio
between the duration of the ON state and the total period duration.
By adapting the amplitude of the PWM signal, for example using a
dedicated levelling circuit, an/or by changing the duty cycle using
the controlling unit 220, different average values of the control
signal 216 are achievable. Therefore, the PWM signal is suitable
for driving the power switch Q1 selectively into either closed,
open or linear mode, as required by the method in accordance with
aspects of the invention. Applying the PWM signal to the capacitor
Cl, one terminal of which is connected to the gate of Q1, further
helps to filter and smooth the current in-rush that is detected on
input 212.
[0043] The embodiment 300 shown in FIG. 3 comprises a driver device
310 in which a single converter circuit 315 is shared in time by a
plurality of lighting functions, wherein each lighting function may
require one of a plurality of available power inputs 312, 312', of
which two are illustrated, without limiting the invention to the
number of two. Each power supply input 312, 312' is associated with
a dedicated switching circuit 314, 314', of which each one is akin
to the switching circuits described in previous embodiments. The
switching circuits are controlled by respective control signals
316, 316', which are generated in this example by the common
controlling unit 320, and which implement the same functionality
that has been described for the control signals 116, 216 in the
context of the previous embodiments. In another embodiment,
separate controlling units may as well be used for generating the
plurality of control signals.
[0044] Time shared converters are for example used in automotive
lighting device. When a turn indicator, TI, and parking light, PL,
function are both requested by the car, the converter supplies both
the TI and PL
[0045] LEDs using a time-sharing schedule and using the same input
power supply, for example 312. When the TI is switched off, i.e.
every 300 ms, input supply 312' must be used to supply power to the
PL alone due to practical and regulation constraints. Once the TI
comes back on, power is detected on input supply 312, which is then
used to replace input 312'. There is thus a periodic switching
between power supply inputs 312 and 312', which is implemented by
controlling the switching circuits 314, 314' accordingly. In
accordance with this embodiment of the invention, before the
corresponding switching circuits 314, 314' go into their closed
mode, they are driven for 1-2 ms into a linear mode using control
signals 316 and 316' respectively, in which they act as a
resistance in order to smooth the current in-rush that is otherwise
fed forward to the converter circuit 315. In this scenario, the
proposed method avoids the periodic in-rushes at the converter
circuits input, which would otherwise be detected erroneously as
driver failure due to input overload.
[0046] Based on the examples and illustrations that have been
provided, a person with ordinary skills in the art will be able to
provide a computer program for implementing the control process in
accordance with aspects of the invention, without undue burden and
without requiring further inventive skills.
[0047] It should be understood that the detailed description of
specific preferred embodiments is given by way of illustration
only, since various changes and modifications within the scope of
the invention will be apparent to the skilled person. The scope of
protection is defined by the following set of claims.
* * * * *